> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fapost.in/llms.txt
> Use this file to discover all available pages before exploring further.

# Building a Solution

> Composer-distributed extensions that ship with the application.

A Solution is a vertical product module — HR, recruitment, anything with its own
domain behaviour — distributed as a Composer package under your own vendor.

<Note>
  The external Solution lifecycle is planned, not product-complete in Core. The
  boundaries below are enforced today; the installation and release tooling around
  them is still being built. Treat this page as the contract you will be held to,
  not as a finished walkthrough.
</Note>

## Boundaries

A Solution must not live under `app/Solutions` inside Core. It is an external
package, resolved through Composer like any other dependency — see
[Development setup](/extending/development-setup) for the two-lane workflow.

Its public contracts belong in `fapost/foundation`. Dependency-free primitives
belong in `fapost/support`. Neither package may reference `App\…`, and neither may
absorb business logic that belongs to Core.

Front-end components are possible, but only through the agreed build and publish
contract. A Solution cannot drop Vue files into a running application — the
builder front end is compiled ahead of time.

## What a Solution typically contains

Most Solutions are a combination of pieces documented elsewhere in this section:

<CardGroup cols={2}>
  <Card title="Node handlers" href="/extending/flow-nodes/handler-contract">
    So flows can act on your domain.
  </Card>

  <Card title="A data accessor" href="/extending/data-accessors">
    So conditions can read your data without duplicating it.
  </Card>

  <Card title="Builder configuration" href="/extending/builder-ui">
    So your nodes can be configured on the canvas.
  </Card>

  <Card title="Migrations" href="/extending/plugins">
    Subject to the same migration isolation rules as Core.
  </Card>
</CardGroup>

## Before you start

Read [Choosing an extension type](/extending/choosing-an-extension-type) first. The
most common mistake is building a Solution for something that has no domain of its
own and should have been a Plugin — or, more expensively, building one for
something that belongs in Core.